EHRC Homepage | New Category | Your Questions

Paul Nelson replies:

Actually, the situation is quite the reverse. It is Haeckel's questionable drawings which have survived in textbooks and popular publications, whereas the evidence casting doubt on his "biogenetic law" lives in the primary literature, largely neglected.

The biogenetic law is not the basis of modern developmental biology. In fact, the biogenetic law was collapsing under (a) the weight of contrary evidence and (b) its impracticality as a research tool, even before the rise of the neo-Darwinian synthesis (Rasmussen 1991). In 1894, Edmund Wilson, in his lectures to the Marine Biological Laboratory at Woods Hole, held the biogenetic law primarily responsible for "the vast number of elaborate hypothetical phylogenies which confront the modern student in such bewildering confusion" (1895, p. 103). As he continued:

It is...a just ground of reproach to morphologists that their science should be burdened with such a mass of phylogenetic speculations and hypotheses, many of them mutually exclusive, in the absence of any well-defined standard of value by which to estimate their relative probability. The truth is that the search after suggestive working hypotheses in embryological morphology has too often led to a wild speculation unworthy of the name of science; and it would be small wonder if the modern student, especially after a training in the methods of the more exact sciences, should regard the whole phylogenetic aspect of morphology as a kind of pedantry unworthy of serious attention. (Wilson 1895, pp. 103-104)

Thus, by 1909, the Cambridge embryologist Adam Sedgwick, for instance, was already looking for alternatives to the biogenetic law; as he wrote:

If after 50 years of research and close examination of the facts of embryology the recapitulation theory is still without satisfactory proof, it seems desirable to take a wider sweep and to inquire whether the facts of embryology cannot be included in a larger category. (Sedgwick 1909, p. 176)

In 1922, in his critical review of the concept, Walter Garstang argued that the biogenetic law "has evoked little but controversy and confusion" (1922, p. 81). As he continued:

As it is not to the credit of science that Zoology should harbor a "law" which, like a creed, may be accepted or rejected at pleasure, and as I believe the basis of this law is demonstrably unsound, I venture to make a renewed attempt to define the points at issue. (Garstang 1922, p. 81)

Many of the founders of neo-Darwinism (e.g., August Weismann) were intellectual refugees from the magical land of recapitulationism. Others, such as William Bateson (1894), abandoned the research program of "ontogeny recapitulates phylogeny," after their initial enthusiasm, because they discovered that ontogeny did not recapitulate phylogeny in even an approximate sense, and furthermore that the "law" suffered from grave methodological defects (1894, p. 8).

The biogenetic law is false, and has been known to be so for well over a century.

For further information, see Michael Richardson et al., "There is no highly conserved stage in the vertebrates: implications for current theories of evolution and development," Anatomy and Embryology 196 (1997): 91-106.

See also:

Hall, Brian. 1995. Homology and Embryonic Development. Evolutionary Biology 28: 1-37.

Horder, T.J.. 1989. Syllabus for an Embryological Synthesis. In Complex Organismal Functions, eds. D.B. Wake and G. Roth. New York: John Wiley.

Nieuwkoop, P.D. and Sutasurya, L.A. 1976. Embryological evidence for a possible polyphyletic origin of the recent amphibians. Jl. Embry. exp. Morph. 35(1):159-167.

Raff, Rudolf, Gregory Wray, and Jonathan J. Henry. 1991. Implications of Radical Evolutionary Changes in Early Development for Concepts of Developmental Constraint. In New Perspectives in Evolution, eds. L. Warren and H. Koprowski; New York: Wiley-Liss; pp. 189-207.

These citations provide a good introduction to the relevant literature.


Bateson, W. 1894. Materials for the Study of Variation. Baltimore: Johns Hopkins Univ. Press [1992 reprint].

Garstang, W. 1922. The Theory of Recapitulation: A Critical Re-Statement of the Biogenetic Law. Linnean Journal - Zoology 35: 81-101.

Rasmussen, N. 1991. The Decline of Recapitulationism in Early Twentieth- Century Biology: Disciplinary Conflict and Consensus on the Battleground of Theory. Journal of the History of Biology 24:51-89.

Sedgwick, A. 1909. The Influence of Darwin on the Study of Animal Embryology. In Darwin and Modern Science, ed. A.C. Seward. Cambridge: Cambridge Univ. Press, pp. 171-184.

Wilson, E. 1895. The Embryological Criterion of Homology. Sixth Lecture, Summer Session 1894. Biological Lectures Delivered at the Marine Biological Laboratory of Wood's Hole. Boston: Ginn & Co., pp. 101-124.

______________________________________________________ Ó 2010 Arthur V. Chadwick, Ph.D.